\Pen*nat"u*la\, n.; pl. L. {Pennatul[ae]}, E.
{Pennatulas}. [NL., fr. L. penna a feather.] (Zo["o]l.)
Any one of numerous species of {Pennatula}, {Pteroides}, and
allied genera of Alcyonaria, having a featherlike form; a
sea-pen. The zooids are situated along one edge of the side
branches.